The present invention relates to a connecting device and process for the manufacture of ducts for heating, conditioning, ventilation and similar applications.
It is known that a great number of types of conditioning/heating ducts are present on the market which differentiate from each other in terms of manufacturing methods, materials, sizes and assembling and hooking systems. Among these types there is one contemplating manufacture of ducts of suitable section starting from flat sandwich panels consisting of a core of insulating material interposed between two thin metal sheets.
Manufacture of ducts for the above mentioned applications is carried out following a sequence of operating steps comprising a starting step of suitably arranging the panels of insulating material cut to size to form the different segments of the expected ducts.
In particular, in the case of straight ducts of a rectangular section and consisting of a single panel, two bevels inclined at an angle of 45° are first of all formed at longitudinal and opposite edge bands of the same panel, which bevels are designed to form a junction line of the duct segment defining one of the longitudinal edges of the duct itself. In addition, formed within the panel are three V-shaped notches with a 90° opening and adapted to define longitudinal bending lines.
In accordance with the known art, the above mentioned 45° bevels and V-shaped notches are provided to be fully and uniformly covered with a layer of glue by a brush spreader or a spray gun, for example, after setting them free of any residual material resulting from cutting operations.
Before carrying out bending of the panel along the V-shaped notches to shape the segment into a duct it is necessary to wait for about 15 minutes to enable the glue solvent to evaporate. This period of time varies depending on the temperature and humidity and can become much longer under particular unfavorable weather conditions. Practically, the gluing operation terminates when the glue is dry to the touch and is to be carried out in a very ventilated area and in compliance with all measures provided by the regulations in force concerning environmental sanitation and safety.
The connecting process briefly described above for the manufacture of ducts for heating, conditioning, ventilation through use of glue has many limits and drawbacks.
In fact, first of all, it contemplates a stop in the duct building process for a period of time that is sometimes rather long and often cannot be exactly foreseen, due to the fact the glue drying time is not always the same.
In addition, the special glues used to obtain a steady and safe union of the duct sides are very expensive and therefore greatly affect the overall costs for manufacturing said ducts.
Finally, it is to be pointed out that the operations for glue application and assembling of the glue-coated parts are characterized by a non negligible complexity of execution and all expedients, measures and safety precautions prescribed by the regulations in force are required to be complied with because the glue may contain inflammable or toxic components.